Islamist Hamas said Ahmed Al-Jabari, who ran the organization's armed wing, the Izz al-Din Al-Qassam Brigades, died along with his son after their car was targeted by an Israeli missile.
"The occupation has opened the gates of hell on itself," Hamas' armed wing said following the targeted killing of its commander.
Top Hamas terrorist Ismail al-Ashkar said, "The resistance's options are now open and they include suicide attacks and quality attacks in Israel cities."
The IDF said Jabari's assassination marks the beginning of Operation Cloud Pillar against Gaza terrorists.